An animal should (be altruistic to) any infant, regardless of whether or not they are related. br > c, meaning altruism occurs when its benefit to a relative times r, the coefficient of relatedness between the relative and the actor, outweighs the costs to the actor altruism should only occur in certain species that meet key criteria. fr < fa, meaning the fitness of relatives is worth less than the actor's fitness, so altruism should never occur